Process of manufacturing sound-records.



No. 836,646; PATBNTED NOV. 20, 1906.

T. H. MACDONALD.

PROCESS OF MANUFACTURING SOUND RECORDS. APPLICATION FILED FEB. 29. 1904.

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awonl'oz UNITED, STATES PATENT oFFIoE- THOMAS H. MACDONALU, OF BRIDGEPORT, CONNECTICUT. PROCESS OF MANUFACTURING SOUND-R ECOl RDS- Specification of Letters Patent.

Patented not. 20. 1 eoe.

Application filed February 29, 1904. Serial No. 195,917-

To all whmn it may concern: I

Be it known that I, TnoMAs H. MACDON- ALD, a resident of Bridgeport, Connecticut, have invented a new and useful Improvement in Processes of Manufacturing Soundquality.

' and renewed. These and al In carrying out the invention an original sound-record (preferably a record of varying depth) is made in the usual way-i. 8., by engraving upon a tablet of the ordinary waX like material. From this original an electrotype master is made in the usual waythat is, by first coating the Wax record with a coating of plumbago or other conducting material and then depositing thereon electrolytically a layer of suitable metal, such as copper. The copper master is separated from the wax original and after careful cleaning and polishing is plated with a plating of metal, such as silver, which is acted upon by a metalloid. This silver-plating. is preferably applied by means of the washing method--i. e., applied by a camels-hair brush--rather than by electrodeposition. The copper plate is thoroughly cleaned and a silvering paste brushed over its surface. This paste is prepared by dissolving silvernitrate in water, precipitating the silver in the form of a chlorid by means of common salt, Washing the precipitate, and dissolving it in potassium cyanid. The solution is filtered, if necessary, and mixed with enough whiting to make athin paste. In practice it is found that twentytwo parts of silver nitrate to forty-two parts of cyanid of potassium give good results. The metallic negative is now used for obtaining duplicates by the direct electrodeposition of the metal upon the silverplated master or negative. To make this operationcommercially successful, it is necessary that a separating-film should intervene between the negative and the electrodeposited ositive or duplicate, so that the two may e separatedwithout injury to either. This film must be exceedingly thin, so as not to obliterate or modify the form of the soundvibrations, and it should be uniform, continuous, and capable of being readily a plied other con itions necessary to insure success are met by sub- ]ectmg the silver-plated negative to the action of a chemicalagent, such as the sulfid of an alkali or alkaline earth. Potassium suliid has given the best results thus far obtained. Sulfur fumes have also been successfully used. In carryingput this part of the operation a weak solution of potassium sulfid prepared by dissolving one-half ounce of the sulfid in one gallon of water is flowed over the metal negative and at'once poured off. This causes the formation of an exceedingly thin but uniform and continuous light-brown film of a sulfid .of the metal acted upon, (in this case sulfid of silver.) The surface is. then Washed with clean water and placed in the platin bath. A duplicate record of the desired tiickness is now deposited electrolytically, copper being the metal preferred. The surfaces of the negative and positive can now be readily separated by introducing the blade of a knife between the edges at .any point. The duplicates may be then polished and finished in any suitable way, as by nickel-plating. Duplicates made in this manner are not only very durable, but they have acoustical qualities of a very superior order, readily distinguishable by the ear from records made in wax or otherplastic material. The noticeable characteristics are fidelity to the original sounds and a very. rich and agreeable tone quality.

The formation of the separating-film (in the form of a salt or com ound of the metal constitutin the surface 0 the negatlve) may be accomphshed in other ways. For exameat or other method of oxidation and fair re-" sults obtained; but the best mode n0w contemplated of applying the principle of said 1nvention is that stated above.

Other modifications will readily suggest themselves to persons skilled in the art t which the invention relates.

The negative can be used for the roduction of a large number of duplicates; ut the separating-film must be renewed after every two or three duplicates.

For the purpose of graphically illustrating the invention reference is made to Figures 1 and .2 of the accompanying drawings, in which- I Fig. 1 is an isometric sectional perspective view showing a tablet with a record formed thereon havin an electrodeposition superimposed upon t e record-face of the file, the silver surface may be oxidized by V IIO tablet, and Fig. 2 is .a cross-sectional View showing the negative formed by the electrodepos tion properly backed and a record electrically deposited thereon with a separating-film between the metallic negative and the record ,thus deposited.

Referring to Fig, 1 of the drawings, 1 rep resents a record-tablet of any suitable material, preferably wax or wax-like materials,

oxid or compound, depositing thereon arating-filmt (indicated by the dark line m Fig. 2) is then applied to the surface of the negative. The negative 2 thus backed up and provided with the separating-film 4 constitutes a metallic negative from which duplicatesare obtained by the direct electrical do [position of metal 5 thereon in the usual way. lhe duplicate having thus been deposited upon the metallic negative is then readily separable from the metallic negative, this being rendered possible by the resence of the se arating-film hereinbefore escribed.

y se arating-film as herein used is meant a 1" m which permits the actual bodily separation of the negative and the positive metallic record as distinguished from a layer of some substance whlch-acts merely as a partition between the two bodies. By separating the negative and positive is not meant the destruction of the former, but the true bodily separation of the two intact.

What is claimed is 1. Theprocess of making metallic copiesof sound-records by forming upon a metallic record-bearing surface a thin film by chemical treatment of said surface, electrodepositing a metallic plate on said film, and separating the two metallic bodies.

2. The process of making metallic sound-- records by forming on a metallic record-bearing surface a thin separating-film of a metalge Y electrolysis a plate of suitable metal, and separatin the two metallic bodies.

3.. The recess. of making metallic duplicate soumf records by forming upon a metallic negative of disk form by acting chemically u on the surface thereof, a separating-film, e ectrodepositing thereon a plate of suitable metal, and bodily separating the negative and positive.

4..The cate soun -records by acting upon the surface of a metallic record-bearing surface with an agent such aspotassium sulfid, thereby forming a film so thin as not to impair the form of the recorded vibrations, depositing electrolytically a layer of metal thereon, and bodily separating the two metallic bodies.

5. The process of making duplicate soundrecords by forming a silver-plated negative, treating the surface thereof to form a thin coating of a compound of silver, then electrodepositing a layer of metal on said film, and

separating the duplicate from said negative.

6. The process of (in licating sound-records by forming a metal 1c negative, forming thereon a sulfid of the metal whereof the surface of said negative is formed, electrodepositing a positive thereon, and separating the negative and positive.

7. The process'of making sound-records by "forming a metallic negative, treating the same with a solution of an alkali or alkalineearth sulfid, de ositing a positive thereon, and so )arating t 0 negative and ositive.

8. he process of making soun -records by forming a silver-plated metallic negative, treatin the same with a solution of an alkali or alka inc-earth sulfid, depositing a positive thereon, and separating the negat ve and positive.

9. The process of making sound-records by forming a silver-plated metallic negative, treatin the same with a solution'of potassium sulfid, dc )ositing a positive thereon, and sepmatin the negative and ositive.

10. The process of ma king sound-records by forming a silver-plated record-surface, forming thereon a thin coating of a compound of silver, depositing a metallic layer thereon,

and se arating the two layers.

' 11. he process of makin' metallic soundrecords by forming a meta lic. record-bearing surface, forming thereon a sulfid of the -metal whereof said surface is composed, elec-.

trodepositing av metallic layer thereon, and se arating the two metallic bodies.

11 testlmony whereof I have signed this specification in the presence of two subscribing. witnesses.

THOMAS MACDONALD.

Witnesses:

C. B. INGALLS, A. B. KEOUGH."

recess of making metallic dupli- 

